Global Migration

• Author: Jeffrey G. Williamson
• Position: Laird Bell Professor of Economics at Harvard University. This article draws heavily from his 2005 book with Timothy J. Hatton, Global Migration and the World Economy: Two Centuries of Policy and Performance (Cambridge, Massachusetts: MIT Press)

Two centuries of mass migration offers insights into the future of global movements of people

World migration has been going on for centuries, and free mass migration-of those not coerced, like slaves and indentured servants-has been going on for the past two. The reasons people move are no big mystery: they do it today, as they did two centuries ago, to improve their lives. What has changed is who is migrating and where they come from.

Both the demand for long-distance moves from poor to rich countries and the ability of the potential migrants to finance those moves have soared over the past two centuries. As the gap in living standards between the third world and the first world widened in the 20th century, the incentive to move increased. At the same time, improved educational levels and living standards in poor parts of the world-and falling transport costs globally, thanks to new technologies-have made it increasingly possible for potential emigrants to finance the move.

Thus, over time, poorer and poorer potential migrants, those who live the farthest from high-wage labor markets, have escaped the poverty trap. This emigration fact implies an immigration corollary that has important political backlash implications: relative to native-born host country populations, world immigrants have declined in "quality" over time-at least as judged by the way host country markets value their labor.

Adding to the rising demand for emigration, the population pool of the most mobile young adults increased as poor countries started the long process of economic modernization. Every country passes through a demographic transition as modern development unfolds: improved nutrition and health conditions cause child mortality rates to fall, thereby raising the share of surviving children in the population. After a couple of decades, this glut of children becomes a glut of young adults, exactly those who are most responsive to emigration incentives.

These demographic events were important in pushing poor Europeans overseas in swelling numbers in the late 19th century and even more important in pushing poor third-world workers to the first world in the late 20th century. At the other end of this demographic transition are the rich industrial countries, where population aging contributes to a scarcity of working adults and thus to a first-world immigration pull that reinforces the third-world emigration push.

Thus, the dramatic rise in world mass migration after the 1960s should have come as no surprise to any observer who has paid attention to history. But to truly understand world mass migration-and what might lie ahead-it is not enough to look at only the past few decades. We must assess the present relative to a past that stretches back over two centuries.

The first wave

The discovery of the Americas stimulated a steady stream of voluntary migration from Europe. High transport costs and big risks ensured that only the richest and most fearless made the move. Furthermore, distance mattered: the longer the move, the bigger the cost, and the greater the positive selection. These voluntary migrants, however, were dwarfed by those who came under contract and coercion. About 11.3 million journeyed to the New World before 1820, of whom 8.7 million were African slaves. Another large European emigrant group consisted of indentured servants and convicts, whose migration costs were financed by others. Thus, coercion and contracts were the chief means by which the labor-scarce New World recruited workers before the 19th century.

However, once started, the transition to free migration-which marks a decisive shift in the history of intercontinental migration-was spectacular: the share of free migrants in the total jumped from 20 percent in the 1820s to 80 percent by the 1840s. The combination of incentives, constraints, and policies that underlie the transition speak directly to the global migrations of today.

In the first three decades after 1846, the numbers of emigrants averaged about 300,000 a year; they more than doubled in the next two decades; and, after the turn of the century, they rose to over a million a year (see chart). Their countries of origin also changed dramatically. In the first half of the century, emigrants came predominantly from the richer parts of Europe-the British Isles, followed by Germany. By mid-century, they were joined by a rising tide of Scandinavian and other northwestern European emigrants and, in the 1880s, by southern and eastern Europeans.

[ GRAPHICS ARE NOT INCLUDED ]

The overwhelming majority of these emigrants headed for the Americas, the United States in particular. U.S. immigration from 1846 until the imposition of quotas in the 1920s follows closely the total European emigration pattern. After the mid-1880s, significant numbers of emigrants also went to South America, primarily Argentina and Brazil, and to Canada after the turn of the century. Another stream linked the United Kingdom...